As is known in the art, various electrophotographic devices include a scanning unit for imaging an item to be scanned prior to transferring that image to, e.g., paper, transparencies, photographic paper, or a digital image storage means. Typically a scanning unit, such as a flatbed scanning unit of a well-known type used in electrophotographic devices such as scanners, printers, or copy machines, includes a contact glass on which an item to be scanned or copied is placed.
A conventional scanning unit associated with an electrophotographic device, unless the device is intended to be portable, is fixed in place. That is, the scanning unit repeatedly scans a defined, fixed area on or in the electrophotographic device, and the item to be scanned must be correctly positioned over this defined area. For this reason, it is important to properly place an item to be scanned or copied on the scanning unit to ensure that the full surface of the item is imaged. To aid the user in properly positioning an item such as a sheet of paper to be scanned, a reference marker, often in the shape of an arrow, is usually provided to indicate the desired positioning of at least one corner of the item.
Such reference markers are typically placed adjacent the scanning unit contact glass, e.g., by molding or embossing the desired design into the material framing the contact glass, by imposing an adhesive decal, or by use of a paint or dye. Such methods of (and structures for) providing a reference marker are suitable for their intended purpose, but suffer from a number of disadvantages. A reference marker molded or embossed into the scanning unit may be difficult for the user to see. Further, reference markers defined by molding, embossing, painting, or by use of a decal may deteriorate over time. That is, the reference marker may be partially or wholly worn or rubbed off, reducing user convenience.